The invention relates to a packet, in particular a cigarette packet, with flaps which can be bonded to one another by pressure and, if necessary, heat, for example tube-forming flaps and closing flaps, the packet preferably consisting of a laminate possessing a heat-weldable outer layer.
Laminates have proved to be a packaging material having particular advantages for the cigarette industry. Using a laminate, substantially air-tight and aroma-tight packets can be produced from a one-piece blank.
In the case of laminates having outer layers or coatings of a heat-weldable plastic, flaps of the blank which are to be bonded to one another are bonded by heat-welding, namely by application of heat and pressure. If the packet is appropriately designed, this welding is used on the one hand for a so-called tube-forming flap, which runs in the longitudinal direction of the packet, and on the other hand for end flaps which form the packet seal in the zone of the end faces.
Subjecting the packets to heat and pressure proves difficult in practice, for various reasons. The contents of the packet are sensitive to exposure to these conditions. In particular, the pressure to be applied must be carefully controlled. On the other hand, the parts of the blank which are to be bonded to one another are not always completely planar. As a result of preceding folding processes, but also as a result of the behavior of the flexible laminate, waviness is encountered in the zone of the flaps which are to be bonded to one another. On the other hand, however, an aroma-tight and air-tight seal can only be achieved, and guaranteed, if the flaps in question are bonded to one another without leaving any gaps.
It is the object of the invention so to design and prepare a packet of the type described, or its blank, that when producing bonds, requiring pressure, between parts of the blank, a bond which is free from gaps, and is tight throughout, can be produced with relatively little pressure.